Domestic energy savings with geyser blankets

Abstract

The Demand Side Management intervention of having hot-water cylinders (geysers) wrapped with blankets showed some serious defects in the installations in the Western Cape. Energy audits by the Cape Peninsula University of Technology Measurement and Verification Team revealed a number of shortcomings, including poorly secured blankets; inadequate covering of the piping of at least 1 meter on the inlet and 2 meters on the outlet side; exposed parts of the cylinder and fittings; and inaccurate determination of the water temperatures. In order to quantify the extent of such defects, a pilot study was conducted in the CPUT laboratories to measure the seriousness of such deviations. Results quoted in this paper indicate that standing losses could be reduced by up to 27,0 per cent by properly wrapping both the hot-water cylinder plus 3 meters of piping. If only the hot-water cylinder is covered properly, then the standing losses could be reduced by up to 21,7 per cent. By selecting lower temperature set-points of the geyser between 650C and 500C, the energy required to re-heat the water inside the cylinder could be reduced by up to 16,0 per cent, or approximately 1 per cent per 10C. This paper therefore exposes inherent problems encountered in the Western Cape project, which need to be addressed before future roll-out programmes of this nature are launched elsewhere.